Isotopic niches of fishes in coastal, neritic and oceanic waters off Adélie land, Antarctica

Abstract : We used the stable isotope method to investigate the ecological niches of Antarctic fishes, with d13C and d15N as proxies of fish habitats and dietary habits, respectively. Muscle isotopic signature was measured for each of 237 delipidated tissue samples from 27 fish species collected offshore Ade'lie Land, East Antarctica. Overall, d13C values ranged from 25.3& to 18.2&, thus allowing characterizing of the fish habitats, with inshore/benthic species having more positive d13C signatures than offshore/pelagic ones. No clear difference in the d13C values of pelagic fishes was found between species living in neritic and oceanic waters. Overall, the d15N signatures of neritic pelagic and epibenthic fishes encompassedw1.0 trophic level (3.1&), a higher difference than that (1.4&) found within the oceanic assemblage. Fishes with the lowest and highest d15Nvalues are primarily invertebrate- and fish-eaters, respectively. The isotopic niches of fishes illustrate the different mechanisms allowing coexistence, with most fishes segregating at least by one of the two niche axes (d13Cand d15N).Muscle isotopic values also document interindividual foraging specialization over the long-term in coastal benthic fishes, but not inmore offshore pelagic species. Finally, the d15Nsignatures of fishes overlap with those of penguins and seals, indicating that seabirds and marine mammals share the upper levels of the Antarctic pelagic ecosystem with some large fish species. In conclusion, the concept of isotopic niche is a powerful tool to investigate various aspects of the ecological niche of Antarctic fishes, thus complementing the use of other conventional and non-conventional approaches.
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Submitted on : Monday, August 8, 2011 - 11:31:21 AM
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Yves Cherel, Philippe Koubbi, Carolina Giraldo, Florian Penot, Eric Tavernier, et al.. Isotopic niches of fishes in coastal, neritic and oceanic waters off Adélie land, Antarctica. Polar Science, Elsevier, 2011, 5, pp.286-297. ⟨10.1016/j.polar.2010.12.004⟩. ⟨hal-00613950⟩



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